1. Field of the Invention
This invention relates to electrodeless lamp apparatus and, in particular, to quadrature-coupled microwave electrodeless lamps. Accordingly, it is a general object of this invention to provide new and improved apparatus and lamps of such character.
2. General Background
Various electrodeless lamps have been described in the prior art. For example, U.S. Pat. No. 4,070,603, issued Jan. 24, 1978 to Regan et al., discloses an apparatus in which the light source is of the type including a microwave power source and an electrodeless lamp having a light transmitting envelope and a volatile fill material which emits light upon breakdown and excitation. The outer conductor is a metallic mesh.
U.S. Pat. No. 4,178,534 to McNeill et al., issued Dec. 11, 1979, mentions that electrodeless lamps have the potential for extremely long life, because there is no need for the arc discharge to be in contact with any material either electrodes (i.e. since there are none) or the lamp envelope.
Conventional prior art low pressure, compact, fluorescent, microwave electrodeless lamps present an infinite voltage standing wave ratio (VSWR) to its microwave power source prior to starting. Under this condition, the microwave power source (typically a solid state device which provides drive power to the lamp) is subjected to operating extremes (current, and/or voltage, and temperature) which degrade the device performance, leading to premature failure.